sendmail not able to send mails to outer domain

[oracletest]

Hi

I am trying to configure a mail server for my company since, last week. And now, this thing is driving me nuts.
I hav tried with Postfix and Sendmail, but the error is similar for both, as both are not helpful to send mail to outer domain, like yahoo or gmail.

i hav read zillions of forums and articles of doing that. Now my manager is ultimately asking to replace the OS, as I am using centOS, and not willing to replace it for this mare issue.

Can anybody suggest wat to do, or replacing the OS is the ultimate solution...???

i hav installed DNS server as well, but don know if MX records are set, as i made an entry of MX record to named file, it gives error, by rejecting the change made. Do it really effects the configuration???

I am Newbie to the Linux world, and tried and installed all the required
applications on my own,by using GOOGLE the gr8. But this thing is really messy, as it shows no sign of mercy


Any kinda help wud b truely appreciated, n plz don mind if i wrote anything annoying in anyways,as i am highly irritated over it..

thanks

[Kieren]

If this problem is the same as what I've had it's due to your ISP blocking out going connections on port 25 to stop hackers turning peoples computers into spam bots

You can check if your ISP has blocked port 25 by simply trying to connect to an external mail account (such as Hotmail) with:

telnet mx1.hotmail.com 25

[oracletest]

hey

well i checked with my ISP, they are now having all ports open for me on my network.
then i tried to telnet hotmail and yahoomail servers, but no response.
But the thing is why hotmail or yahoomail servers will reply to telnet from me, isnt it a security hazard?

N how can i check otherwise, if my port is blocked or not?

[Irithori]

The telnet check is good for anything not encryted
and if the protocol is cleartext.

SMTP (port 25) is one of this protocols.
Say "helo localhost"

Another example would be HTTP

telnet http://www.linuxforums.org 80
Say "GET /index.html"

So, if you dont get a connection with telnet, your mailservers wont also.

Do you get a "connection refused", or a "connection timeout"?

[oracletest]

yes i got a connection timed out error..
heres the error on window

# telnet mx1.hotmail.com 25
Trying 65.55.37.88...
telnet: connect to address 65.55.37.88: Connection timed out
Trying 65.55.37.104...
telnet: connect to address 65.55.37.104: Connection timed out
Trying 65.55.37.120...

[Irithori]

just tried.
This is, what should happen:

telnet mx1.hotmail.com 25
Trying 65.55.92.152...
Connected to mx1.hotmail.com.
Escape character is '^]'.
220 snt0-mc2-f46.Snt0.hotmail.com Sending unsolicited commercial or bulk e-mail to Microsoft's computer network is prohibited. Other restrictions are found at http://privacy.msn.com/Anti-spam/. Violations will result in use of equipment located in California and other states. Wed, 11 Nov 2009 01:16:55 -0800 
quit
221 snt0-mc2-f46.Snt0.hotmail.com Service closing transmission channel
Connection closed by foreign host.

[oracletest]

this is wat i getting

# telnet mx1.hotmail.com 25
Trying 65.55.92.184...
telnet: connect to address 65.55.92.184: Connection timed out
Trying 65.54.188.72...

i checked again with my ISP, they say, none of ports are bolcked.
then wat cud be done in this case??

[Kieren]

Could it be a firewall on your end?

[oracletest]

I hav disabled the firewall as well.

Tell me one more thing, is it required to configure a DNS server to send mails to outer domain??

[Irithori]

yes.
If a mailserver has no MX, than this can be used by the receiving mailserver as a factor to rise the SPAM probability of your mailserver-